Go to User CP
http://img163.imageshack.us/img163/9752/usercp.gif
Scroll down to Your Profile, Click on Edit Your Details
http://img607.imageshack.us/img607/744/editdetails.gif
Enter your custom user title
http://img26.imageshack.us/img26/788...omeruserle.gif
Do not forget to save changes
http://img811.imageshack.us/img811/4194/savechanges.gif